The present invention relates to a plasma processing apparatus which performs dry etching processing or plasma CVD processing of a semiconductor substrate, and more particularly to a microwave plasma processing apparatus which produces high-density and uniform plasma stably with low pressure and is suitable for uniform processing of a substrate having a large diameter.
A plasma processing apparatus for a semiconductor device introduces processing gas into a plasma processing chamber (hereinafter referred to as a processing chamber) having a vacuum atmosphere therein to produce plasma in the dry etching process and produces ions and radical having chemically high reactivity by ionization and dissociation of the processing gas. The active particles act physically and chemically to etch and remove a desired portion of a processed film on a semiconductor substrate so that a device pattern is formed. In such an apparatus, in order to attain the etching process faithful to a mask pattern and having a so-called reduced side etching, it is necessary to effect processing by low-pressure plasma to increase the directivity of ions and reduce the effect of radical for advancing the etching isotropically. However, since the density of ions and radical is reduced in the low-pressure plasma, it is necessary to produce high-density plasma even in the low pressure in order to ensure the processing speed.
As a method of producing the low-pressure and high-density plasma, there are known methods described in, for example, U.S. Pat. Nos. 4,776,918 and 4,985,109 (corresponding to European Patent Applications 87115349.0 filed October 1987 and 90101864.8 filed January 1990, respectively). In the methods, the intensity of an electromagnetic field of microwaves is increased by a cavity resonator just before the microwaves are introduced into the processing chamber and the microwaves having the increased intensity of the electromagnetic field is introduced into the processing chamber through slots provided in an end surface of the cavity resonator on the side of the processing chamber so that energy is applied to electrons with the increased intensity of the electric field to produce plasma.
Further, JP-A-2-017636 discloses a method in which a coil for generating a magnetic field is disposed around a plasma production chamber in order to produce the low-pressure and high-density plasma so that an ECR (Electron Cyclotron Resonance) occurs in the plasma production chamber.